44 lines
1.4 KiB
Python
44 lines
1.4 KiB
Python
|
"""
|
||
|
|
Geographic utilities: point-in-polygon testing via ray casting.
|
||
|
|
"""
|
||
|
|
|
||
|
|
|
||
|
|
def point_in_polygon(lat: float, lon: float, polygon_coords: list) -> bool:
|
||
|
|
"""Check if a point is inside a polygon (supports Polygon and MultiPolygon)."""
|
||
|
|
if not polygon_coords:
|
||
|
|
return False
|
||
|
|
|
||
|
|
# MultiPolygon: check each polygon
|
||
|
|
if isinstance(polygon_coords[0], list) and isinstance(polygon_coords[0][0], list):
|
||
|
|
for polygon in polygon_coords:
|
||
|
|
if polygon and isinstance(polygon[0], list):
|
||
|
|
ring = polygon[0] if isinstance(polygon[0][0], list) else polygon
|
||
|
|
if point_in_ring(lat, lon, ring):
|
||
|
|
return True
|
||
|
|
return False
|
||
|
|
|
||
|
|
# Single Polygon: use first ring (outer boundary)
|
||
|
|
ring = polygon_coords[0] if isinstance(polygon_coords[0], list) else polygon_coords
|
||
|
|
return point_in_ring(lat, lon, ring)
|
||
|
|
|
||
|
|
|
||
|
|
def point_in_ring(lat: float, lon: float, ring: list) -> bool:
|
||
|
|
"""Ray casting algorithm for point-in-ring test."""
|
||
|
|
n = len(ring)
|
||
|
|
inside = False
|
||
|
|
|
||
|
|
x, y = lon, lat
|
||
|
|
p1x, p1y = ring[0]
|
||
|
|
|
||
|
|
for i in range(1, n + 1):
|
||
|
|
p2x, p2y = ring[i % n]
|
||
|
|
if y > min(p1y, p2y):
|
||
|
|
if y <= max(p1y, p2y):
|
||
|
|
if x <= max(p1x, p2x):
|
||
|
|
xinters = (y - p1y) * (p2x - p1x) / (p2y - p1y) if p1y != p2y else p1x
|
||
|
|
if p1x == p2x or x <= xinters:
|
||
|
|
inside = not inside
|
||
|
|
p1x, p1y = p2x, p2y
|
||
|
|
|
||
|
|
return inside
|